#!/bin/bash -eu
# Copyright 2020 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################

path=$1
function=$2
fuzzer=$3
tags="-tags gofuzz"
if [[ $#  -eq 4 ]]; then
  tags="-tags $4"
fi

# makes directory change temporary
(
cd $GOPATH/src/$path || true
# in the case we are in the right directory, with go.mod but no go.sum
go mod tidy || true
# project was downloaded with go get if go list fails
go list $tags $path || { cd $GOPATH/pkg/mod/ && cd `echo $path | cut -d/ -f1-3 | awk '{print $1"@*"}'`; } || cd -
# project does not have go.mod if go list fails again
go list $tags $path || { go mod init $path && go mod tidy ;}

if [[ $SANITIZER = *coverage* ]]; then
  fuzzed_package=`go list $tags -f '{{.Name}}' $path`
  abspath=`go list $tags -f {{.Dir}} $path`
  cd $abspath
  cp $GOPATH/ossfuzz_coverage_runner.go ./"${function,,}"_test.go
  sed -i -e 's/FuzzFunction/'$function'/' ./"${function,,}"_test.go
  sed -i -e 's/mypackagebeingfuzzed/'$fuzzed_package'/' ./"${function,,}"_test.go
  sed -i -e 's/TestFuzzCorpus/Test'$function'Corpus/' ./"${function,,}"_test.go

  # The repo is the module path/name, which is already created above in case it doesn't exist,
  # but not always the same as the module path. This is necessary to handle SIV properly.
  fuzzed_repo=$(go list $tags -f {{.Module}} "$path")
  abspath_repo=`go list -m $tags -f {{.Dir}} $fuzzed_repo || go list $tags -f {{.Dir}} $fuzzed_repo`
  # give equivalence to absolute paths in another file, as go test -cover uses golangish pkg.Dir
  echo "s=$fuzzed_repo"="$abspath_repo"= > $OUT/$fuzzer.gocovpath
  # Additional packages for which to get coverage.
  pkgaddcov=""
  # to prevent bash from failing about unbound variable
  GO_COV_ADD_PKG_SET=${GO_COV_ADD_PKG:-}
  if [[ -n "${GO_COV_ADD_PKG_SET}" ]]; then
    pkgaddcov=","$GO_COV_ADD_PKG
    abspath_repo=`go list -m $tags -f {{.Dir}} $GO_COV_ADD_PKG || go list $tags -f {{.Dir}} $GO_COV_ADD_PKG`
    echo "s=^$GO_COV_ADD_PKG"="$abspath_repo"= >> $OUT/$fuzzer.gocovpath
  fi
  go test -run Test${function}Corpus -v $tags -coverpkg $fuzzed_repo/...$pkgaddcov -c -o $OUT/$fuzzer $path
else
  # Compile and instrument all Go files relevant to this fuzz target.
  echo "Running go-fuzz $tags -func $function -o $fuzzer.a $path"
  go-fuzz $tags -func $function -o $fuzzer.a $path

  # Link Go code ($fuzzer.a) with fuzzing engine to produce fuzz target binary.
  $CXX $CXXFLAGS $LIB_FUZZING_ENGINE $fuzzer.a -o $OUT/$fuzzer
fi
)
